The invention concerns an actuator of an electrohydraulic gas exchange valve train of an internal combustion engine, said actuator comprising an actuator housing which can be fixed in the internal combustion engine, said actuator housing comprising a bore, a valve lash adjuster being received axially displaceable in said bore, said lash adjuster comprising a compensating housing for operating the gas exchange valve and further comprising an axial stop for limiting an outward travel of the compensating housing out of said bore and said axial stop comprising radially overlapping stops which are fixed in axial direction on said bore and on said compensating housing.
It is known that the variability of the opening and closing times of gas exchange valves and of the maximum valve lift is achieved in electrohydraulic valve trains in that a so-called hydraulic linkage together with a pressure chamber is arranged between a cam of a camshaft and the gas exchange valve, wherein the volume of the pressure chamber can be continuously reduced through an electromagnetic hydraulic valve into a pressure relief chamber. Depending on the reduction volume of the hydraulic medium, the cam lift produced by the camshaft is converted fully, partially or not at all into a lift of the gas exchange valve.
The present invention relates to that part of the valve train actuating system that is situated on the gas exchange valve side and whose movement corresponds to the lift of the gas exchange valve. An actuator of the pre-cited type is known, for example, from DE 10 2007 030 215 A1. The actuator housing in this case is a bushing that is screwed into a hydraulic unit that is fixed in the cylinder head of the internal combustion engine and in whose bore a hydraulically loaded slave cylinder and, adjoining this, a hydraulic valve lash adjuster of a known type are mounted for axial movement. In the disassembled state of the actuator or of the hydraulic unit, the compensating housing of the valve lash adjuster is not seated on the gas exchange valve, and the compensating housing is prevented from falling out of the bore of the actuator housing through the axial stop that is then active. The stops of the axial stop on the compensating housing are made in the form of a polygonal snap ring that is inserted into an annular groove on the outer peripheral wall of the compensating housing to protrude in radial direction therefrom, and the stops on the bore are constituted by a shoulder that is formed by a bore opening with a reduced diameter.